Apparatus and method for capping a cylindrical tube



United States Patent [56] References Cited UNITED STATES PATENTS [72]Inventors m Mr H "e "Hu a ell. wmmm CDPK 2446 9999 till 797 1 9588 4797.9 4432 8508 .223 .m h 0 lu a n .m c .m m C. N e m m b 8 8 m 6m... J 9mk k n "w wo w r6 y F7 Ab o dm w. mm. d P P um$ AFPA n 5 3 2247 [Ill TheMead Corporation Primary Examiner-Charles W. Lanham Dayton0hio AssistantExaminer-Michael J. Keenan a corporation of Ohio. Attorney lohn W.Donahue 6 Claims, 2 Drawing Figs. [52] US. ABSTRACT: Apparatus andmethod for securin ends of cores, drums, and the like. A novel [54]APPARATUS AND METHOD FOR CAPPING A CYLINDRICAL TUBE 113/121, g caps onthe 29/243.52, l 13/ l pivotally mounted lnt.Cl...............................................821d51/00 roller performs a longitudinallyadvancing spinning action [50]FieldofSearch..................................... 113/246, upon theskirt ofa pre-applied cap. Upon withdrawal of the l2lA, l2lAB, IZlAA,121C, 1204, lE; 72/207, spinning head the roller automatically imparts anarrow 208, 2 I4, 226; 29/ 243.52; 72/80, 84-87 peripheral crimp to thespun down skirt.

Patented Aug. 25, 1970 3,525,311

INVENTORS STANLEY c. ELDER FREDERICK J. EBBERS FIG.2 By M W ATTORNEYAPPARATUS AND METHOD FOR CAPPING A CYLINDRICAL TUBE BACKGROUND OF THEINVENTION This invention relates to the field of capping cylindricaltubes. In general, the caps involved may be covers such as end closuresfor drums or annular reinforcing rings for the ends of fibrous coressuch as are used in rolls of paper or the like. In either case it isusually desirable to slip the cap over the end of the tube andthereafter to secure it in place by lateral deformation against the tubewall. Typical prior art apparatus for performing this operation is shownin Pottle U.S. Pat. No. 2,403,998 and Magill US. Pat. No. 2,633,095.

It will be observed that the prior art devices are limited to rathersimple forming operations and moreover are cumbersome to use. Frequentlyit is desirable to secure the cap by general deformation over a largeskirt area with a narrow peripheral crimp for anchoring. Heretoforethere has been no simple practical tool for accomplishing this compoundaction. In general, it has been necessary to employ a pair ofindependently operated tools; one for general deformation and the otherfor crimping.

SUMMARY OF THE INVENTION This invention provides an apparatus and methodfor performing the aforesaid deformation and crimping operations simplyand efficiently by rotating the tube about its longitudinal axis andthen merely advancing and withdrawing a roller which is mounted on acontrol bar in a novel pivotal fashion. In the preferred embodimentthere is employed a cap with a flared skirt which is spun down againstthe tube by the longitudinally advancing roller. At the end of thespinning action, the withdrawal of the control bar causes the roller topivot away from the cap, but with a swinging motion which initiallymoves the roller crimpingly inward toward the cap. The pivotal movement,as above described, is produced by mounting the roller on a foot whichis in turn pivotally connected to the control bar. Crimping is achievedby locating the pivot point longitudinally forward of the roller workingsurface; forward being the direction of roller longitudinal advanceduring the genreal spinning action. The mechanical principles thereininvolved are more fully explained in the drawings and the description ofthe preferred embodiment which follow.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration in sectionof a preferred embodiment showing a pair of cooperating rollerssimultaneously spinning down the inside and outside skirts of an annularcap.

FIG. 2 is an enlarged diagrammatic illustration of a crimping operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment forthis invention is generally shown in FIG. 1 wherein a cylindrical fibercore 1 has been cut away to expose an inserted inner tool 2 whichextends through an aperture in chuck for cooperation with outer tool 3.Tools 2 and 3 are shown working on an annular cap 4 which has beenseated at the end of core 1 by the action of chuck 5 working against atail stock (not shown). Cap 4 is of the type generally shown in DodgeUS. Pat. 1,358,531 but modified for ease of seating by flaring the innerskirt as at 6 and the outer skirt as at 7. Tools 2 and 3 are eachcomprised ofa control bar 8, a foot 9, and a roller 10. Pivot pins 11,provide pivotal support for feet 9, thereby enabling feet 9 to swingaway from their respective working surfaces as indicated by the brokenlines of FIG. 1. The swinging action is rotationally limited in theworking-surface direction by walls of channels which are cut mediallyinto feet 9 thereby permitting feet 9 to straddle control bars 8. Asshown in partially cutaway fashion on tool 3, wall 12 bears against theedge of control bar 8 during longitudinal advance of roller 10.

While the aforesaid rotationally limited pivotal action is an importantaspect of this invention, the means for limiting the pivotal rotationare a mere matter of choice. For instance, the function of wall 12 couldbe well served with a pin, lug, or other projection.

In operation core 1 is rotated about its longitudinal axis while tools 2and 3 simultaneously perform longitudinally advancing spinning actionsagainst flared skirts 6 and 7 thereby bringing cap 4 into intimatecontact with core 1. When tools 2 and 3 reach the ends of theirlongitudinal strokes, the spinning action is complete and the crimpingaction commences.

FIG. 2 illustrates the mechanics of the crimping action by showing thetool of this invention at two different positions during crimping. Thesolid lines represent the tool at the end of the aforesaid longitudinalstroke and the broken lines represent the tool at that point where thecrimping action is maximum. The crimping action as shown in FIG. 2 isrepresentative of the operation of either tool. Corresponding to the twotool positions, the wall 13 is shown solid (spun down) and broken(crimped).

Crimping is begun by applying a withdrawal force to control bar 8 whilemaintaining roller 10 in contact with wall 13. This sets up a frictionalresisting force F acting in the indicated direction and tending torotate foot 9 clockwise about pivot pin 11. However, since the point ofpivotal rotation is longitudinally forward of the roller workingsurface, the effect of force F is to urge roller 10 toward wall 13. Itwill be appreciated that this is a 3 dimensional operation becausecontinuing rotation of the core causes movement of wall 13 in adirection which is locally perpendicular to the plane of FIG. 2. F isessentially a static frictional force because roller 10 spins about itsmounting axis to give its working surface a circumferential velocitymatching the spinning velocity of wall 13.

As shown in FIG. 2, movement of roller 10 toward wall 13 is resisted bya normal force N acting in the indicated direction. Forces N and F arein fact reacting forces automatically set up to oppose a driving force(not shown) which, during crimping, is transmitted by control bar 8through pivot pin 11 and on out to roller 10. It should be observed thatN is a continuously present force which is essentially constant duringthe spinning action and variable during crimping. It is apparent thatclockwise rotation of foot 9 cannot occur unless the sum of theclockwise moments about pivot pin 11 exceeds the sum of thecounterclockwise moments about the same point. In mathematical form therequirement is stated as follows:

Fr cos 9 Nr sin 6 where r is the radius and 0 is the lead angle as bothare illustrated in FIG. 2.

The above requirement imposes a limitation upon the use of the inventivetool. This can be seen by observing that F and N have magnitudes whichare directly proportional. That is:

where p. is the coefficient of friction of roller 10 against wall 13.Upon combining the above equations and performing other indicatedoperations, the limitation becomes:

This means that for a given lead angle there can be no crimping actionunless the coefficient of friction is above some minimum value. If thestated condition is satisfied, then the tool will move as illustrated inFIG. 2 and a crimp will be achieved. Upon completion of the crimp, foot9 will swing clear of wall 13 and follow control bar 8 through thewithdrawal stroke. If p. has a magnitude less than the minimum valuestated by the above equation, then the rotation of foot 9 will beresisted by excessive counterclockwise moments, and the foot will merelyfollow the withdrawal of control bar 8 without crimping wall 13.

As far as the inventive apparatus is concerned, the above discussionmerely outlines restrictions on use. However, this inventioncontemplates a process as well as an apparatus. For the process there isa necessary limitation which is somewhat the reverse of the restrictionupon the apparatus. Thus, if it is desired to practice this invention tocrimp a cap of some given material, then it becomes necessary to selecta roller of any suitable material, and, upon completion of the usualspinning action, to apply a pivotally supported withdrawal force. Themechanics of the crimping operation require that the point of pivotalsupport be longitudinally forward of the roller working surface andfurthermore positionally restricted such that:

In the preferred embodiment of this invention the lead angle has a valueof about l0 degrees. Application of the appropriate equation indicatesthat the preferred apparatus may be used in any situation wherein p. hasa value no less than about 0.l76. When working with metal on metal in aclean condition, the coefficient of friction is generally always abovethat value. For steel on steel p. has a value of about 0.53 which iswell above the computed minimum. Under lubrication conditions, however,y. may be expected to drop to a value of around 0.1 or less. This meansthat the preferred embodiment should be used under clean nonlubricatedconditions.

Alternatively, for practicing the inventive process to crimp a cleansteel cap with a clean steel roller, the coefficient of friction assumesa fixed value of 0.53, and there arises a lead angle limitation.Application of the appropriate equation dis closes that under the statedconditions 0 may be no greater than about 28 degrees.

As a matter of engineering practice, therefore, the apparatus of thisinvention preferably should be designed with a lead angle less thanabout 28 degrees. While being positioned to accommodate this preference,the pivot pin of the preferred embodiment may be further positioned tofix the amount of crimp desired. It is easily shown that the crimp A iscontrolled by' fixin'g the radius land the lead angle 0 in accordancewith the following equation:

We claim:

I. In a machine for capping a cylindrical tube, cap deforming apparatuscomprising:

a roller for peripheral rolling contact against a wall of a cap;

a foot for supporting the roller during said contact; and

a longitudinally moveable control bar supporting the foot byrotationally limited pivotal connection thereto;

the rotational limit for said pivotal connection being fixed to supportthe foot for a longitudinally advancing cap deforming action, and thepoint of pivotal connection being positioned longitudinally forward ofthe roller working surface thereby swinging said working surfacecrimpingly toward the cap upon application of a withdrawal force to thecontrol bar.

2. Cap deforming apparatus according to claim 1, and further comprisinga pivot pin for provision of said pivotal connection.

3. Cap deforming apparatus according to claim 2 said foot being providedwith a medially extending channel for straddling the control bar andproviding the rotational limit for said pivotal connection.

4. in a machine for capping a cylindrical tube a pair of cap deformingapparatus each of said apparatus being constructed according to claim 3,one of said apparatus being mounted for deformation of the interiorskirt of an annular cap and the' other said apparatus being mounted forcooperating deformation of the exterior skirt of the same annular cap.

5. A pair of apparatus according to claim 4, each of said apparatushaving its pivot pin located for a lead angle less than about 28degrees.

6. The method of reinforcing a resilient cylindrical tube comprising thesteps of:

l. seating at an end of said tube a metal cap provided with a 2.rotating the tube about its longitudinal axis; and

3. while rotating the tube:

a. urging a metal deforming roller into rolling peripheral contact withthe cap; and b. while maintaining said rolling peripheral contact:

i. advancing the roller in the longitudinal direction thereby deformablyremoving the flare from the flared skirt and forcing the cap intointimate contact with the tube; and

ii. thereafter longitudinally withdrawing the roller by applying apivotally supported withdrawal force at a point longitudinally forwardof the roller working surface but with a lead angle the tangent of whichis less than the numerical value of the coefficient of friction of theroller against the cap thereby provid-- ing a frictionally inducedpivotal crimping action.

